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Tasklist

FS#69050 - Firefox 84.0 not proxying to 127.0.0.42

Attached to Project: Arch Linux
Opened by Reginald (Uqbar) - Monday, 21 December 2020, 11:47 GMT
Last edited by Andreas Radke (AndyRTR) - Friday, 07 May 2021, 08:38 GMT
Task Type Bug Report
Category Packages: Extra
Status Assigned   Reopened
Assigned To Jan Alexander Steffens (heftig)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No

Details

Description: Firefox 84.0 is not SOCKSv5 proxying connections to 127.0.0.42. On Windows 10, same version works just fine.


Additional info:
* Firefox: 84.0-1
* OpenSSH: 8.4p1-2
* Remote machine has "OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n 7 Dec 2017" (likely irrelevant)

Steps to reproduce:
1. Create a SOCKSv5 proxy via ssh with a command like: ssh -D 127.0.0.1:1080 user@remote.host
2. On remote host have a local web server listening on *
3. Configure Firefox to use SOCKSv5 proxy on 127.0.0.1:1080
4. Open URL: http://127.0.0.42:80 (127.0.0.1 and ::1 are not proxyed by design)
5. Open URL: https://www.ipify.org/

Expected results:
Step no.4: Firefox to show the remote local webserver homepage
Step no.5: Firefox to show a web page with remote server's public IP, not local client's.

Actual results:
Step no.4: Firefox shows "Unable to connect - Firefox can’t establish a connection to the server at 127.0.0.42."
Step no.5: Firefox shows a web page with remote server's public IP.

Notes:
Step no.5 demonstrates the proxy is actually working.
On Windows 10, same Firefox version downloaded from Mozilla servers yields expected results with exactly the same remote server and target URLs.
This task depends upon

Comment by Reginald (Uqbar) - Wednesday, 21 April 2021, 15:54 GMT
Firefox is mocking Chrome behaviour.
Moreover they forgot to update the proxy setting notes that still read:
"Connections to localhost, 127.0.0.1/8 and ::1 never use the proxy" (translated from my language).
It should read instead:
"Connections to localhost, 127.0.0.0/8 and ::1 never use the proxy"

Firefox used to be different. Now it's conformed! Cool!
As of now, Firefox won't proxy 127.0.0.0/8 any more *by default*.

The workaround is to manually set the configuration toggle called "network.proxy.allow_hijacking_localhost".

1. Open meta-url about:config and "accept the risk"
2. In the search box type "hijacking" (w/o quotes)
3. Toggle the value to TRUE
4. 127.0.0.0/8 can now be proxied again.
Comment by Reginald (Uqbar) - Friday, 07 May 2021, 08:38 GMT
  • Field changed: Percent Complete (100% → 0%)
It's not been fixed at all, Andreas Radke (AndyRTR).
Simply Firefox definitely and permanently changed its behavior by not proxying any destination address within 127.0.0.0/8.
You can close this ticket, of course. But you cannot tell it's working. It simply doesn't.

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